There is a known technology of capturing surrounding areas behind a vehicle with a rear camera instead of a conventional optical rearview mirror and presenting them on a display. There is a known technology of detecting positions of eyes of a driver or movements of the eyes and, in accordance with a detection result, changing a position of a display area to be presented on a display (for example, see Japanese Laid-open Patent Publication No. 2014-045265).
With a conventional optical rearview mirror, when a driver moves his head from side to side, a range formed by a virtual image changes, and therefore a range wider than an area of the actual mirror may be viewed. However, an electric mirror displays an actual image of a two-dimensional video which is different from a virtual image by the conventional optical rearview mirrors. Therefore, the driver who used to use a conventional optical rearview mirror may take unconscious action to move his head for changing the range of view so as to obtain necessary information. Thus, there is a demand to provide appropriate required information for a driver in accordance with the driver's unconscious action.